Deutsche Tagung f ¨ur Forschung mit ... - SNI-Portal

Nanostrukturen und Grenzflächen Poster: Do., 13:00–15:30 D-P293
Innershell excitation of free nano particles
Burkhard Langer 1,3 , Harald Bresch 2 , René Lewinski 2 , Peter Brenner 2 , Roman
Flesch 2 , Christina Graf 2 , Tatiana Martchenko 4 , Omair Ghafur 4 , Marc
J. J. Vrakking 4 , Eckart Rühl 1
1 Institut für Chemie und Biochemie, Freie Universit – 2 Institut für Physikalische
Chemie I, Universität Würzburg, Am Hubland, 97074 Würzburg – 3 Max-Born-Institut
für Nichtlineare Optik und Kurzzeitspektroskopie, Max-Born-Straße 2A, 12489 Berlin
– 4 FOM Institute AMOLF, Amsterdam, The Netherlands
Using a continuous particle beam we have studied inner shell excitations in free nano
particles when they were exposed to monochromatic synchrotron radiation. This approach
goes beyond related work, where elastic light scattering has been studied in the
vacuum ultraviolet regime [1,2]. It is also complementary to single, trapped nanoparticles
that have been studied by synchrotron radiation in the soft x-ray regime [3]. Our
particles were transferred into the gas phase by an aerosol generator. An additional
differential mobilisation analyser (DMA) made it possible to generate a continuous
beam of size selected nano particles that was focussed into the vacuum chamber by
an aerodynamical lens. This approach allowed us to prepare free nano particles which
were produced by colloidal chemistry. We have measured the total electron yield in
order to characterise the electronic structure of nano particles in the region of their
inner shell excitations.
First experiments were performed on size selected NaCl nano particles (radius: 50-175
nm) in the region of the Cl 2p and the Na 1s excitation. Measurements in the region
around the O 1s absorption threshold show that these particles contain only little
water. In contrast, nanoscopic salt particles (Na2SO4·10 H2O) that contain chemically
combined water show a significant absorption in this region which might be of interest
to study the binding structure of such water. In addition, we have studied the influence
of coatings to the electronic structure of free core-shell particles. Here we used ZnS
particles (radius = 60 nm) with a 5 nm SiO2 shell.
This work is supported by the Bundesministerium für Bildung und Forschung (BMBF)
grant no.: 05 KS4WW1/7 and the Deutsche Forschungsgemeinschaft (SFB 410-TP C8)
[1] J.N. Shu, K.R.Wilson, M. Ahmed, S.R. Leone, C. Graf, E. Rühl, J. Chem. Phys.
124, 034707 (2006).
[2] J.N. Shu, K.R.Wilson, A.N. Arrowsmith, M. Ahmed, S.R. Leone, Nano Lett. 5,
1009 (2005).
[3] M. Grimm, B. Langer, S. Schlemmer, T. Lischke, W. Widdra, D. Gerlich, U. Becker,
R. Flesch, E. Rühl, Phys. Rev. Lett. 96, 066801 (2006).